Smoking bans have made the air healthier in bars and restaurants, but may have made the air just outside the establishments more hazardous, University of Georgia researchers have found.

Nonsmoking diners and imbibers sitting in outdoor patios or sidewalk seating areas connected to the bars or restaurants are picking up doses of secondhand smoke, the scientists found.

In fact, nonsmokers who volunteered to sit in the outdoor seating areas had levels of a tobacco by product in their bodies up to 162 percent higher than when they first sat down, said Luke Naeher, a professor in UGA’s environmental health science department.

Collaborating with researchers in the federal Centers for Disease Control and Prevention and the Northeast Health District, Naeher and other UGA researchers measured levels of a substance called cotinine.

Naeher’s research team assigned 20 nonsmoking volunteers to spend six evening hours in one of three outdoor areas for the study – outside a downtown Athens bar, outside a restaurant near downtown or outside UGA’s main library.

“We’re looking at real-world settings,” Naeher said.

After six hours, the volunteers gave a saliva sample, which the researchers tested for cotinine, a nicotine byproduct often used as an indicator of tobacco exposure.

Volunteers who hung out where smokers gather outside a restaurant saw their cotinine levels more than double. Nonsmokers outside a bar had their cotinine increase by even more, up to 162 percent.

The study is published in this month’s issue of the Journal of Occupational and Environmental Hygiene.

Few restaurant or bar patrons are exposed to six hours of secondhand smoke at a stretch – but workers could be, Naeher said.

Cotinine unexpectedly even went up in the library group, by an average of 16 percent – possibly because one of them passed by a smoker as the volunteer walked downtown to give researchers a saliva sample, Naeher said.

Previous studies have shown that restaurant and bar smoking bans reduce the incidence of heart attacks and respiratory illness among people inside the establishments.

“The question is, is it an environment that warrants concern or further study?” Naeher said. “The answer is, we don’t know yet.”

The researchers aren’t quite ready to declare outdoor cafes a new health hazard for those that may inhale secondhand smoke there – including children, restaurant and bar workers, and pregnant women and their unborn children.

But secondhand smoke contains numerous carcinogens, and scientists believe there is no safe level of exposure, Naeher said.

“We feel like it’s something we need to be taking a look at,” said Lou Kudon, one of the authors of the study. Kudon is program manager for the Athens-based Northeast Health District, which includes Clarke and nine other area counties.

Next, the researchers will measure levels of a chemical called NNAL, a known carcinogen, in nonsmokers who spend time in outdoor places where people smoke.